This invention relates to a driving technique for a liquid crystal matrix display panel wherein the brightness is dependent on the effective value of an applied voltage.
It is well known that matrix display panels having signal lines and scanning lines in a matrix and a plurality of pixels at the crossings of these lines typically twisted nematic liquid crystal matrix panels possess the dependency of its brightness of respective ones of the pixels on the effective value of applied voltages thereto. For the display panels of a 5.times.7 dot matrix with a cursor line, an electrode structure per character (character, number, symbol or the like) is set up by five data column electrodes 1, seven scanning row electrodes 2 and a single cursor line electrode 3 as depicted in FIG. 1. The respective scanning row electrodes 2 and the cursor line electrode 3 are conventionally scanned in a line sequential fashion for displaying characters.
The greater the voltage margin given as follows the better the contrast and viewing angle characteristics of the liquid crystal panel: ##EQU1## where V.sub.rms (ON) is the effective value of an ON voltage applied across a respective one of the liquid crystal pixels V.sub.rms (OFF) is the effective value of an OFF voltage applied thereto and N is the number of the scanning lines.
It is however obvious that the greater the number N of the scanning lines the smaller the voltage margin as seen from FIG. 2 which is plotted with the voltage margin against the number N of the scanning lines. With the above line sequential scanning technique which scans the single cursor line electrode 3 as well as the seven scanning row electrodes 2, the number N of the scanning lines increases with a resultant decrease in the voltage margin d. This leads to the problems with degradation of the contrast and viewing angle characteristics of the liquid crystal panel.